Haemosporidian parasites are the agents of malaria. Countless vertebrates are affected by haemosporidians each year. Haemosporidians have been shown to be evolving at rapid rates; leading to new species of haemosporidians being discovered and new host associations being made. Adaptive molecular evolution was detected in an important hemoglobin degradation gene, falcilysin. At multiple sites across multiple genes involved in important functions signatures of negative selection were detected. The signatures of selection across non-hemoglobin degradation genes were indicative of evolutionary conservation when compared to the more variable hemoglobin degradation genes. This is probably due to the important role the hemoglobin degradation genes play in haemosporidian metabolism. A survey of local passerines detected a parasite prevalence rate of 57%. This included three genera of haemosporidians detected across six lineages and two more distantly related sequences. Leucocytozoon was detected for the first time in Mississippi songbirds, indicating the importance of surveying for understanding haemosporidian evolution and range.